Nonograms, also known as Picross or Griddlers, are picture logic puzzles where you use number clues to reveal a hidden image. The numbers on the side of the grid describe the sequences of filled-in squares in that row or column. For instance, a clue like '2 3' means there's a block of two filled squares, followed by at least one empty square, and then a block of three filled squares. Use the tools to either fill a square with color or mark it with an 'X' to indicate it's empty. Carefully cross-reference the row and column clues to solve the puzzle and bring the hidden picture to life!